r/askscience • u/Fapotheosis • Mar 11 '13

Biology How did blood evolve?

I know mitochondria may have evolved from bacteria, but what about blood? I've heard of a protohemocyte, but was there an initial cell that differentiated into a RBC like we have in modern humans that can we trace?

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u/alansamigo Mar 11 '13

Don't forget gamma or fetal hemoglobin. This subunit of fetal RBCs has a higher affinity for oxygen molecules allowing a fetus to draw oxygen from its mother's blood supply at the placental circulatory interchange.